Tube-bending machine



June 8 1926.

c. T. WOLDERS TUBE SENDING MACHINE Filed Nov. l

2 she ets sheet 1 m Q% a \l 'lllullll Patented June 8, 1926.

COENELIS THEODOR'US WOLDEBS,

OF MIDDELB'UBG, NETHERLANDS.

TUBE-BENDING MACHINE.

Application filed November 16, 1925, Serial No. 69,446, and in Netherlands October 11, 1923.

My invention relates to machines for bending tubes when cold.

Machines for this kind are generally pro vided with a core, one end of which is connected to a fixed point and'the other end of which is rounded and extends to a position directly above the circumference of a rotatable clamping block, in which a groove is provided to receive the tube to be bent.

In order to bend a tube with a machine of this kind, the tube is slid over the core while its end is fixed to the circumference of the clamping block. Thereafter the clamping block is slowly rotated whereby the tube is bent around the clamping block, the wall of the tube being supported by the rounded end of the core.

In practice difficulty is experienced in correctly bending tubes with machines of this kind for the following reasons:

Firstly the wall of the tube is not homogeneous all over, so that the outside of the tube at some points is during bending subject to heavy stretching, while at other points it is not stretched.

Secondly the cross section of the core should be less than the inner diameter of the tube to be bent as otherwise it is impossible to slide the tubes over the core, as those tubes are usually not quite round and not smooth on the inside. WVhere a space is provided between the core and the tube, the tube has after bending an oval form. Moreover great friction is set up between the core and the tube, so that to effect the bending operation and to draw the tube over the core heavy forces must be exerted.

According to the present invention the above defects are obviated by rotating the core during the bending operation to facilitate which the core is preferably provided with rollers disposed at the circumference of the core. In this way the wall of the tube is so to say rolled, so that a perfectly formed bend is obtained.

According to the invention the rollers are located in openings formed in a freely rotatable container of tubular form, in which a positively driven rotatable spindle is contained, against the circumference of which the rollers bear. When the spindle of the bending machine is rotated, such movement is transmitted to the rollers by reason of the frictional contact they make with its circumference with the effect that these rollers roll over the inner wall of the tube whereby the container can freely follow the movement of the rollers.

The spindle is preferably constructed so that it decreases in cross section towards its end and moreover can be slid relatively to the roller container in an axial direction. In this way by withdrawing the spindle it results that the rollers in the container are permitted to fall down with the effect that the tubes can be slid in and out easily.

According to the present invention the rollers are preferably placed inclined relatively to the axis of the core with the result that during the bending operation of a tube the wall of the latter so to say is rolled and friction of the rollers against the wall of the tube is prevented.

In order that the invention may be clearly understood an embodiment of the same will now be described by aid of the accompanying diagrammatic drawings in which: I

Fig. 1 shows a side elevation of the machine,

Fig. 2 shows a top view of the same, and

Fig. 3 shows a detail on a larger scale of the end of the core.

Referring to the drawings, on a support 1 is rotatably mounted in bearings a shaft 2, carrying a clamping block 3. This block 3 is provided with a semi-circular groove 4 around its periphery. On the circumference of the clamping block 3 a clamping device 5 is arranged adapted to clamp the end of the tube which is to be bent over said block.

At a very small distance above the clamping block 3 lies the end of a horizontally placed core 6, the other end of which is fixed to the support 22 of the machine. Above and below the core are placed rollers 31 for guiding and supporting the tube to be bent.

In order to bend a tube firstly the whole tube is slid over the core 6 and afterwards the end is fixed by means of the clamping device 5 at the circumference of the clamping block 3. This block is then slowly rotated whereby the tube is bent about the block and the end ofthe core prevents the denting of the tube.

According to the invention. the machine for bending tubes is constructed so that the end of the core during the bending operation of a tube is rotated. To this end the core or? r:

is provided with an inner rotatable shaft 8, which is connected to an electroineter 7. On the'end of the shaft- 8 a spindle 9 is connected, preferably of the form as shown in the drawing.

A roller container or sleeve 11 is mounted so as to be freely rotatable on this spindle.

preferably upon ball bearings 10. In this roller container 'openings12 and 13 at'thecircumference of the rollers that the latter canbe slid inwards when the spindle 9 is displaced to the left relative'to the roller container'll (Fig. 3), whereby they are prevented from falling out'of theroller container; This li'as'the' effect as mentioned in the introductory part of the specification.

When the shaft 8 with the spindle 9 are rotated-this movement of the spindle 9 is transferred to the rollers 14- and 15, which in the openings 12 and 13 start to rotate, whereby the roller container 11 can freely follow'the movement of the rollers 1.4 and 15.

The rollercontainer 11 is further at one end connected to a guider 16 which together with the roller containerrotates and at its left end also by means of a ball bearing 1.7 is rotatable in thesleeve 18,- forming the front partof the core 6.

The shaft 8 is rotated by the 'motor 7; T his -motor drives by means of a transmission also a small oil pump 19 (Fig. 2) which supplies oil through a duct to the sleeve 18 from whence the'oil flows througl'i. the guiderlti-a-ndthe roller container 11, from whence the oil is returned to the oil pump to be used over again. All therot-ating parts of the core are therefore lubricated.

Further the shaft 8 is arranged in such a way thatit may be withdrawn over a cer tain distance in the sleeve 18'.

motor 7 on a slidab-le support. However other suitable means maybe also applied for ctlectingthe withdrawingof the shaft.

The openings 12' and 13 containing the rollers 14 and 15 are placed inclined'rela tively to the axialdirection, as is shown with dotted lines in Fig; 3., with the effect that in bending the tube friction between the roller and the tubeis prevented. In

order to be able to bend tubes of different th'e correspondin l This may be effected ina simpleway by arranging the the spindle 9 can be withdrawn-again, in

order to turn the rollers aside;

ll i'th the bending machine referred to hereabove the tubes can" be bent suitably in the form ota helix, for which pur-p'ose on the shaft 2 a clampingbloclr3 is pr'ovided having a'corresponding groove and the motor 7 with the oil pump 19 is mounted upon ash-ding bed 22, the driving part oft-he machine being displaced laterally an amount corresponding with the pitch of tbe" groove in the clamping block: In the draiw ing a shaft 23 is shown which is drivenby the same driving part as servesto drive the shaft 2 and clamping block 31 This shaft 23 drives by means 'of conc wheels 24" and 25 and the wheels 26*a-nd 27' a screw spindle 23, which extends through a corre sponding screw threaded boring-of the slidingbed 22. The wheel 26 is slidablykmounted in axial dir ction-for disengaging the motion.

The motor 7 is slidably mountedim. axialdirection on the block-40. Thisblock etO ha's screw threaded part 4-1 through-which extend the screw-spindles 29 and 30. These: spindles are on the top mounted=in=beai ings 42, which are slidable in a horizontal= direction in awgroove of the yoke 43. The

spindles 29 and 30 are alsorotatable in.v

bearings as fixed in the sliding; bed 22.

This.

sliding bed can slide along:a Support. 4.4,.

which has a groove 1-5, in order that-the spindles 29 and 30'can be. laterally dl'S". placed.

For bendingtubes inthe form-0f a. helix the rollers 31 are also mounted to moveisideways together with the sliding bedI22 :in ac.

cordance with the pitch of-the heli x tobe For thisureason therollers 31 are.

formed. grooved and mounted slidable on shaftsr32.

lVith the machine spiral shape bendscan also beformed by providing 011 the shaft 2 a clamping block 3 havinga-suitableshaped groove, and whereby the blockAO is gradually lifted up by the aid of the screwspim d-les29 and 30.

For this purpose on the shaft-23 asecond:

cone wheel-32 is fixed. This wheel cooper ates with a similar wheel 33, which. bymeans of a transmission drives a horizontal shaft 35. This transmission consists of threepinions 46, 97 and 48, from which the pinion d6 is slidable in axial. directiomfor disengaging purposes. The shaft is provided with a key groove 'by means of which two cone wheels 36 and 37 are slidable over the shaft 35. The wheels 36 and 37 are engaging with cone wheels 38 and 39 fixed on the lower ends of the screw spindles 29 and 30. Means are provided for maintaining the engagement of the pairs of cone wheels 36, 38 and 37, 39 during the laterally sliding movement of the sliding bed 22.

In order to form conical spirals a clamp ing block 3 with a suitably shaped groove is mounted on the shaft 2, while the sliding bed 22 is moved by the machine laterally and the block 40 in an upwards direction, corresponding with the pitch of the winding to be formed.

What I claim as my invention and desire to secure by Letters Patent is:

1. In a machine for bending tubes when cold, in combination, a rotatable clamping block, means for clamping one end of the tube to be bent to the periphery of said clamping block, means for positively rotating said clamping block, a core for supporting the tube to be bent, a sleeve mounted upon one end of said core so as to be freely rotat-able thereon and provided with openings, rollers mounted within openings in said sleeve, a spindle extending centrally through said core and adapted to support said rollers and means for positively rotating said spindle.

2. In a machine for bending tubes when cold, in combination, a rotatable clamping block, means for clamping one end of the tube to be bent to the periphery of said clamping block, means for positively rotating said clamping block, a core for supporting the tube to be bent, a sleeve mounted upon one end of said core so as to be freely rotatable thereon and provided with openings, rollers mounted within openings in said sleeve, a spindle the cross section of which decreases towards its end and extending centrally through and axially slidable within said core, said spindle being adapted to support said rollers which are moved towards and away from the centre of the core in consequence of the axial movement of the spindle and means for positively rotating said spindle.

3. In a machine for bending tubes when cold, in combination, arotatable clamping block, means for clamping one end of the tube to be bent to the periphery of said clamping block, means for positively rotating said clamping block, a core for supporting the tube to be bent, a sleeve mounted up on one end of said core so as to be freely rotatable thereon and provided with openings. rollers mounted within openings in said sleeve, said rollers being inclined to the axial direction of the core a spindle extending centrally through said core and adapted to support said rollers and means for positively rotating said spindle.

4. In a machine for bending tube-s when cold, a core, a sleeve forming an extension to one end of said core and mounted so as to be freely and independently rotatable, said sleeve having two sets of openings arranged therein at an incline to the axial direction of the core, rollers located in each of said openings so as to be similarly inclined, one set of rollers being conical and the other set of rollers barrel shaped, a spindle extending centrally through said core and being axially slidable therein, said spindle having portions, the circumferences of which are shaped correspondingly to the rollers in the two sets said portions being adapted to support said rollers and to move the same laterally when the spindle is moved axially.

In testimony whereof I aflix my signature.

CORNELIS THEODORUS WOLDERS. 

